David Blewett

For example: ```let mut stream = set.range().ge("b").lt("e").into_stream();``` I don't see a corresponding `.range()` method for `OpBuilder`?

Got it. Will fiddle with it.

@jbaiter : it seems the C interface could be simplified a lot if instead of functions specifically for `set::Difference` / `set::Intersection` / `set::Union` , they were defined to take `set::Stream`?...

@BurntSushi : I tried in jbaiter/python-rust-fst#10 , but hit a probably dumb Rust mistake on my part.

@BurntSushi would you mind taking a look at https://github.com/jbaiter/python-rust-fst/pull/10 ? I'm not sure how to fix that compiler error.

@BurntSushi `fstwrapper` is now compiling; thanks! @jbaiter However, now I'm getting segfaults in trying to test the functionality: ``` Python 3.6.3 (default, Oct 3 2017, 21:45:48) Type 'copyright', 'credits' or...

@jbaiter @BurntSushi Sorry this got delayed so long. I have this working now.

The tests pass for me (cPython 3.7, Ubuntu 18.04.1): ``` (fst-test) (dblewett)Wed Sep 12, 15:46 | /home/dblewett/src rusty% py.test python-rust-fst/tests ==================================================================================================================== test session starts ==================================================================================================================== platform linux -- Python 3.7.0b3,...

@jbaiter, @BurntSushi what do you think of this? I wasn't sure about the `UnionSet` name.

@jbaiter is there interest in including this in this package? If not the entire PR, maybe the supporting C functions? it would be cumbersome to do completely outside this package.